1. Field of the Invention
The present invention is directed to an optical connector.
2. Related Art
Mechanical optical fiber connectors for the telecommunications industry are known. For example, LC, ST, FC, and SC optical connectors are widely used.
LC connectors were developed by Lucent as a small-form-factor optical connector in the early 1990s. These connectors have a size that is approximately one-half scale as compared to other standard connector formats. This smaller size permits higher packing densities in distribution frames, resulting in cost savings in the central office and data centers that used them.
The original LC connectors were made by inserting a bare fiber into a hollow ferrule and bonding the fiber into the ferrule with, typically, an epoxy-based adhesive. Conventional LC connector structures and fabrication information are described in U.S. Pat. No. 5,461,690; U.S. Pat. No. 5,579,425; U.S. Pat. No. 5,638,474; U.S. Pat. No. 5,647,043; U.S. Pat. No. 5,481,634; U.S. Pat. No. 5,719,977, and U.S. Pat. No. 6,206,581.
More recently, an LC connector has been developed that uses a hot-melt adhesive instead of an epoxy-based adhesive, as is described in U.S. Pat. No. 7,147,384.
Conventional LC connectors can require a multi-step polishing procedure that must be carefully performed in a controlled manner to achieve a high degree of polish on the end of the fiber and ferrule, while maintaining the proper spherical radius on the end of the ferrule, and while retaining a proper ferrule length. The amount of care needed for this connector preparation is further increased when the connector is an APC (angle polish connector) type.
With these types of requirements, these conventional connectors are not well suited for field installations. As mentioned above, an adhesive is required to mount standard LC connectors to an optical fiber. This process can be awkward and time consuming to perform in the field. Also, post-assembly polishing requires that the craftsman have a higher degree of skill.
Also known are hybrid optical splice connectors, as described in JP Patent No. 3445479, U.S. Pat. No. 7,637,673 and U.S. Pat. No. 7,556,438. However, these hybrid splice connectors are not compatible with standard connector formats and require significant piecewise assembly of the connector in the field. The handling and orientation of multiple small pieces of the connector can result in incorrect connector assembly that may either result in decreased performance or increase the chance of damaging the fiber.
More recently, U.S. Pat. No. 7,369,738 describes an optical fiber connector that includes a pre-polished fiber stub disposed in ferrule that is spliced to a field fiber with a mechanical splice. Such a connector, called an NPC, is now commercially available through 3M Company. Small form factor connectors that are available include the Pretium LC (available from Corning), the Fast LC (available from Fujikura), the Opticam LC (available from Panduit), and Lightcrimp LC (available from Tyco). Another publication, US Publ. No. 2009/0269014 A1 describes a field terminable LC format optical connector with a splice element. Such a connector is also now commercially available through 3M Company.
Another field terminable optical connector is described in US Publ. No. 2011/0044588 A1, incorporated by reference herein in its entirety.